This is a proposal for a five year grant to cover four closely interrelated aspects of research designed to improve our understanding of convalescence after operation and injury, and of support systems for surgical care: Division I - Metabolism, Endrocrinology and Surgical Care; Kinetics in the Early-Phase Catabolism After Injury; Endocrine Determinants of This Phase; Evaluation of the Significance in Wound Healing and Survival; Evaluation of Methods for Modification. Division II - Bioengineering; Establishment of Animal Models for the Use of Extra-Corporeal Oxygenation Systems for Acute Reversible Pulmonary Insufficiency. Division III - Computer Techniques and Intensive Care -Automated Transfusion; Automated Pattern Recognition in Intensive Care. Development of Animal Models for Measurement of Lung Water by Thermaldilution. Division IV - Circadian Oscillation in Animals and Man; Relevance to Clinical Medicine. Biorhythm research in the squirrel monkey, in human volunteer subjects and in adrenalectomized patients. Identification of key components in fluctuations of serum potassium concentrations that might be important in the pathophysiology of sudden death.